1. Field of the Invention
The present invention relates to channel-switching in a digital broadcasting system. More particularly, the present invention relates to a channel-switching apparatus and method in a digital broadcasting system.
2. Description of the Related Art
A digital broadcasting system transmits contents data by compressing them according to channels in a high concentration based upon Moving Picture Experts Group (MPEG) coding standards and then multiplexing them corresponding to a number of channels based upon digital modulation according to transmitting media. Due to these characteristics, the digital broadcasting system can transmit tens or hundreds of channels unlike an analog broadcasting system. The digital broadcasting system can remarkably raise the efficiency of frequency availability over that of the analog broadcasting system. Through this, the digital broadcasting system can advantageously increase the number of broadcast channels. Besides, digital broadcasting system enables multiple utilization of softwares in specialized pay broadcasting and bidirectional service broadcasting, and thus achieve an opportunity that broadcasting industry can develop into multimedia industry. Owing to these reasons, the digital broadcasting system is being widened starting from satellite broadcasting up to cable and ground wave broadcasting, and highlighted as next generation broadcasting technologies.
However, the digital broadcasting system requires long channel-switching (zapping) time owing to digital broadcast signal processing, digital contents protection and bidirectional application. This is not a frequent phenomenon in analog broadcasting, and thus gives inconvenience to digital broadcasting audience. Such long channel-switching time may occur to any of digital cable, ground wave and satellite broadcasting.
Factors that create long channel-switching time in digital broadcasting may include tuning time especially for physical channels, conditional access confirmation for contents protection, decoding for logical channel discrimination and so on. So, digital broadcasting requires long channel-switching time since such several procedures have to be carried out for broadcast receipt. Such long channel-switching time may cause severe dissatisfaction to users.